DESCRIPTION (provided by investigator): Preterm birth is the leading cause of infant mortality worldwide, and also greatly increases the risk of developing serious health complications in childhood and throughout life. Preterm birth, as well as low birth weight infants, are significant public health challenges due to the increased prevalence in these adverse birth outcomes in recent decades. In the US, rates of preterm birth have increased over 30 percent since 1981 and 18 percent since 1990, and now accounts for nearly 13 percent of all live births. Conditions that contribute to preterm birth remain unclear, though the influence of environmental exposures has been immensely understudied. There is recent preliminary evidence that human exposure to bisphenol A (BPA) and phthalates, chemicals used in plastics, personal care products, and other consumer goods may be associated with increased risk of preterm birth and adverse effects on fetal development. In animal studies, BPA and phthalates have been shown to cause oxidative stress, inflammation, and endocrine disruption, mechanism that may contribute to increased risk of altered fetal growth and adverse pregnancy outcomes. This is of particular concern since most of the general population, including pregnant women, are exposed to these classes of compounds on a daily basis. This application proposes to study environmental risk factors for adverse effects on fetal growth and preterm birth among 700 mother/infant pairs selected from a large ongoing cohort study of live born singletons in Boston, MA. The study will utilize state-of-the-art methods for measuring urinary BPA and phthalate concentrations, and for assessing molecular epidemiologic mechanistic pathway markers (oxidative stress, inflammation and endocrine disruption), in biological samples collected during each trimester of pregnancy. Innovative measures of fetal growth and placental function from repeated ultrasound scans during pregnancy will also be explored. The study will utilize patient data and biological samples from an ongoing study and is thus a highly cost-efficient use of research funds. In addition, the proposed study will provide new information on phthalate and BPA metabolism and individual exposure susceptibility among pregnant women, a highly vulnerable segment of the population. The study will also explore whether associations between BPA and phthalates differs based on an innovative classification system to disaggregate preterm births according to underlying etiology. Finally, the study will provide data on the interaction of phthalates and BPA with genetic markers of interest in relation to fetal development and risk of preterm birth.